Different places have different prices; it’s not always terribly expensive.
For example, Illinois used to have a distinction between “personalized” and “vanity” plates, and the personalized ones were a pittance more than randomized plates: a one-time fee of $16 or $18 (can’t remember) and then only the normal renewal cost every year after that for as long as you kept the plate. The rule was you had to start with letter(s) and end with number(s) for a total of up to 7 characters. The obvious choice for many people was their last name and then 1 or something like that. There was even a spot to check on the form if you were OK about getting the next number up if the combo you requested was already taken (so you’d be Smith 27 because there were 26 Smiths before you). My plate ends in “8” (-ate) so I did not check that box.
